Micro-adjustable hydraulic driving device

ABSTRACT

A micro-adjustable hydraulic driving device includes a hydraulic cylinder, a control valve, and a cam. By utilizing a cam, it can precisely control the position of the sliding block and controls the size of the flowing cross-sectional area. So, it can achieve the purpose of precise controlling for the push rod to move slowly or stay at a desired position within the stroke. This invention can precisely control the moving speed and position of the push rod of the heavy load hydraulic cylinder. It can achieve the micro-adjusting effect. It can quickly reverse the moving direction and is easy to operate and control. And, its structure is simple with lost cost.

BACKGROUND OF INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a micro-adjustable hydraulic driving device. Particularly, it relates to a micro-adjustable hydraulic driving device by utilizing a cam. It can precisely control the moving speed and position of the push rod of the heavy load hydraulic cylinder. It can achieve the micro-adjustable function. It can quickly reverse the moving direction and is easy to operate and control. And, its structure is simple with lost cost.

[0003] 2. Description of the Prior Art

[0004] As shown in FIGS. 1 and 2, the conventional hydraulic driving device (or called the hydraulic cylinder control valve 90) controlled by a solenoid can control the movement of a heavy load hydraulic cylinder (not shown). This hydraulic cylinder control valve 90 comprises:

[0005] an inner space 91 for receiving a hydraulic fluid;

[0006] a high pressure port 92, a low pressure port 93, a first port 94 and a second port 95. The first port 94 and the second port 95 connect a hydraulic cylinder (not shown) so as to control its movement such as moving forward or backward;

[0007] a sliding body 96, a middle section of the sliding body 96 has a middle zone 961 so as to guide the flowing direction of the hydraulic fluid; and

[0008] a solenoid 97 to control the movement of the sliding body 96.

[0009] Based on above-mentioned structure of the conventional hydraulic cylinder control valve 90, when the solenoid 97 is not activated or so-called at the “OFF” position, the sliding body 96 is stayed at the upper position inside the inner space 91. At this moment, the hydraulic fluid flows to the first port 94 of the hydraulic cylinder (not shown) and creates a driving force to make the push rod (not shown) of the hydraulic cylinder push rod moving forward.

[0010] Because there is no any staying point between the “ON” and “OFF” positions, the sliding body 96 either stays at the “ON” position or the “OFF” position. Therefore, the push rod (not shown) of the hydraulic control valve 90 either quickly moves to the front end or to the back end. It is impossible to reduce the moving speed or even stay at a middle point.

[0011] In addition, about the conventional grinding machine, it contains a complex hydraulic pipeline system and a control valve to manipulate the movement and moving direction and so on. Especially, when the push rod (sot shown) quickly moves to the protruded end. It will suddenly stop, so that an unavoidable shock occurs. Besides, it cannot change the moving direction swiftly, accelerate, nor move at a very low speed.

[0012] Of course, if the user utilizes the existing ball screws or equivalent linear moving equipment, it can achieve the precise movement, but the cost is too high. In addition, it is not suitable for heavy load hydraulic application.

SUMMARY OF THE INVENTION

[0013] The primary object of the present invention is to provide a micro-adjustable hydraulic driving device. It utilizes a cam to precisely control the moving speed and the position of the push rod of the heavy load hydraulic cylinder.

[0014] The second object of the present invention it to provide a micro-adjustable hydraulic driving device. It can achieve the micro-adjusting effect.

[0015] Other object of the present invention it to provide a micro-adjustable hydraulic driving device. It can quickly reverse the moving direction and is easy to operate and control.

[0016] Another object of the present invention it to provide a micro-adjustable hydraulic driving device. In which, its structure is simple with lost cost.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 shows the conventional hydraulic cylinder control valve when the solenoid is OFF.

[0018]FIG. 2 shows the conventional hydraulic cylinder control valve when the solenoid is ON.

[0019]FIG. 3 shows the system of the present invention.

[0020]FIG. 4 is a cross-sectional view of the control valve showing the sliding block unmoved.

[0021]FIG. 5 is a cross-sectional view of the control valve showing the sliding block moving a little.

[0022]FIG. 6 is a cross-sectional view of the control valve showing the sliding block moving more.

[0023]FIG. 7 is a view showing a roller contacting with the cam.

[0024]FIG. 8 shows another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025] Referring to FIG. 3, this invention is a micro-adjustable hydraulic driving device. It mainly comprises a hydraulic cylinder 10, a control valve 20, and a cam 30.

[0026] With regard to the hydraulic cylinder 10, it extends a slidable push rod 11. This push rod 11 is movable between a first position P1 and a second position P2. The moving distance therebetween is called the stroke S. The hydraulic cylinder 10 has a forward port 12 and a backward port 13 for controlling this hydraulic cylinder 10 by a fluid.

[0027] About the control valve 20, it has a hollow chamber 21 and a sliding block 22 which can move along a straight line. This control valve 20 connects with a pressure source inlet 23, a pressure release outlet 24, a forward driving port 25 that communicates with the forward port 12, and a backward driving port 26 that communicates with the backward port 13. Furthermore, an end of the sliding block 22 is disposed with a micro-adjusting rod 221 that is protruding into the hollow chamber 21. The other end of the sliding block 22 is disposed with a guiding zone 222 and a flow-back zone 223. And, a resilient element 27 is installed in the hollow chamber 21 to push against the sliding block 22.

[0028] Concerning the cam 30, It is a rotatable cam 30 that is controlled by a driving element 31 by precisely controlling a rotation angle of the cam 30. An edge of the cam 30 pushes against an outer end of the micro-adjusting rod 221.

[0029] Therefore, when the driving element 31 rotates to a predetermined angle, the sliding block 221 inside the control valve 20 is pushed by the cam 30 and the sliding block 221 slides to a predetermined position, so as to control the flowing cross-sectional area A (as shown in FIG. 7) of one or both of the forward driving port 25 and the backward driving port 26. Hence, it can precisely control the moving speed of the push rod 11 between the first position P1 and the second position P2 to make it moving slowly or even not moving.

[0030] About the actual operation of this invention, please see FIG. 4. Because the cam 30 does not push the sliding block 22, so the entire sliding block 22 is pushed by the resilient element 27 and moves to the leftmost position. It makes the fluid in the guiding zone 222 flowing through the full-opened forward driving port 25 so that it makes the push rod 11 of the hydraulic cylinder 10 (referring to FIG. 3) full-speed moving.

[0031] As shown in FIG. 5, the cam 30 slight pushes the sliding block 22 the to right for a short distance. Meanwhile, the forward driving port 25 is partially blocked by the sliding block 22 and then forms a semi-opened condition. Its flow rate decreases. As a result, it causes the push rod 11 of the hydraulic cylinder 10 (referring to FIG. 3) moving slower.

[0032] Similarly, once the cam 30 continues to slightly rotate, the forward driving port 25 will be blocked by the sliding block 22 more. Thus, its flow rate becomes less. Hence, the moving speed of the push rod 11 of the hydraulic cylinder 10 (referring to FIG. 3) is getting slower.

[0033] As illustrated in FIG. 6, the sliding block 22 moves to the rightmost position. So, the fluid in the guiding zone 222 will flow to the backward driving port 26. By such switching, the push rod 11 of the hydraulic cylinder 10 (referring to FIG. 3) will move back accordingly.

[0034] Moreover, as shown in FIG. 7, this invention utilizes a driving element 31 (as shown in FIG. 3, such as a stepping motor) to control the rotating angle of the came 30. By doing so, the sliding block 22 can fully or partially block a selected flow path. If using the forward driving port 25 as an example, the flowing cross-sectional area A can be decreased to small area less than the original full-open condition. That is, by precisely controlling the size of the flowing cross-sectional area A, the moving speed of the push rod 11 of the hydraulic cylinder 10 can be precisely controlled.

[0035] Of course, in order to minimize the frictional loss between the cam 30 and the micro-adjusting rod 221, an outer end of the micro-adjusting rod 221 is disposed with a roller 51 for contacting with a periphery of the cam 30.

[0036] In addition, referring to FIG. 8, it illustrates the second preferred embodiment of the present invention. It further comprises a swing arm 52 having two ends. One end is a pivoting end. The other end is a movable end that contacts with a periphery of the cam 30. And, a middle portion of the swing arm 30 pushes the outer end of the micro-adjusting rod 221. By utilizing this simple mechanism, the moving displacement variation of the cam 30 can be reduced proportionally. For example, the original moving displacement variation of the cam 30 is 2 cm. By this swing arm 52, the movable distance of the micro-adjusting rod 221 can be reduced to approximately 1 cm. Anyway, by properly adjust the positions of the cam 30 and the micro-adjusting rod 221, a desired reduction can be obtained.

[0037] The advantages and functions of the present invention can be summarized as follows:

[0038] [1] It can precisely control the moving speed and position of the push rod of the heavy load hydraulic cylinder. In this invention, the cam controls the position of the sliding block and controls the size of the flowing cross-sectional area A. Thus, it can achieve the purpose of precise controlling for the push rod to move slowly or stay at a desired position within the stroke S.

[0039] [2] It can achieve the micro-adjusting effect. Due to the angle of the cam can be divided by N sections (especially for the stepping motor's N steps per cycle), so the sliding block has N positions. If the number N is more, the micro-adjusting effect is better.

[0040] [3] It can quickly reverse the moving direction and is easy to operate and control. This invention utilizes the hydraulic fluid to control the moving position of the sliding block. Hence, the angle of the cam can be precisely controlled. It totally overcomes the sudden change problem of the switching movement of the conventional hydraulic equipment. In this invention, not only the moving speed can be smoothly changed, accelerated, or reversed; but also no shock/vibration occurs. Thus, it is easy to operate and control.

[0041] [4] Its structure is simple with lost cost. The user only needs to add a suitable cam and a proper driving element for the existing control valve. Then, the present invention can work. It does not need any expensive and complicated computer, sensor, hi-tech equipment, etc. Therefore, the cost can be significantly reduced.

[0042] The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention. 

What is claimed is:
 1. A micro-adjustable hydraulic driving device comprising: a hydraulic cylinder extending a slidable push rod, said push rod being movable between a first position and a second position, said hydraulic cylinder having a forward port and a backward port for controlling said hydraulic cylinder by a fluid; a control valve having a hollow chamber and a sliding block movable along a straight line, said control valve connecting with a pressure source inlet, a pressure release outlet, a forward driving port that communicates with said forward port, and a backward driving port that communicates with said backward port, an end of said sliding block being disposed with a micro-adjusting rod protruding into said hollow chamber, other end of said sliding block being disposed with a guiding zone and a flow-back zone, a resilient element installed in said hollow chamber to push against said sliding block; a rotatable cam that is controlled by a driving element via precisely controlling a rotation angle of said cam, an edge of said cam pushing an outer end of said micro-adjusting rod; wherein when said driving element rotates to a predetermined angle, said sliding block inside said control valve is pushed by said cam and said sliding block slides to a predetermined position, so as to control the flowing cross-sectional area of one of said forward driving port and backward driving port, and to control a moving speed of said push rod between said first position and said second position.
 2. A micro-adjustable hydraulic driving device as claimed in claim 1, wherein said outer end of said micro-adjusting rod is disposed with a roller for contacting with a periphery of said cam.
 3. A micro-adjustable hydraulic driving device as claimed in claim 1, further comprising: a swing arm having two ends, one end being a pivoting end, the other end being contacting with a periphery of said cam, and a middle portion of said swing arm pushing the outer end of said micro-adjusting rod. 